Acceleport xp 8 p no nt4

i have an issue where i am upgrading the pc on my existing network of 8 external modems. there are far less functions in this card then the old ISA card used on this network. one if these functions that is not available is “enable error checking for parity and frame errors”
The system is nt4(sp6) the systems connects and dial out to the modems, but the data received at the other end is not correct. all transmitting parameters are correct on the modems.
any clues anyone